1. Field of the Invention
The present invention relates generally to an antenna assembly, and more particularly to an antenna assembly for wireless communication.
2. Description of the Prior Art
With the development of wireless communication, antenna transmitting and receiving signals plays an important role in wireless communication process. The performance of the antenna affects the quality of signal transmission and reception. Consequently researchers in this field focus much their attention on the design or improvement of antenna. In fact, radio frequency module (modulating, filtering, amplifying demodulating signals and so on) is no less important than the antenna for realizing excellent wireless communication. High quality signal transmission and reception needs them to work in concert.
Antenna and radio frequency module are coupled by transmission line, they are coupled directly by the transmission line. For example, both U.S. patent application Ser. No. 090,112,176 and U.S. patent application Ser. No. 91,100,053 disclose a common antenna assembly, just using a transmission line to connect an antenna with a radio frequency module. It is well known that there are many active devices in the RF module, such as amplifier, filter, modulator, demodulator and so on, which are all powered by direct current. During working, these active devices work at a certain state direct current working point. The performances of these active devices depend much on the direct current, and therefore undesired direct current if exits would highly affects the performance of the wireless system. In most cases, antenna is set in the open air. As the environment is complex, static current often arise from the antenna, and it can go through the transmission line into the RF module in former wireless systems. As a result, direct current distortion arises.